Yarn package

ABSTRACT

A PROCESS FOR THE BUILDING OF A STABLE YARN PACKAGE HAVING A YARN TAKEOFF END AND HAVING IMPROVED UNIFORMITY OF MEAN TAKEOFF TENSION WHEREIN THE YARN IS TRAVERSED AXIALLY OF THE PACKAGE IN A SUCCESSION OF TRASVERSE STROKES, THE IMPROVEMENT COMPRISING TRAVERSING THE YARN DURING WINDING IN A MANNER SUCH THAT THE PERCENTAGE OF YARN LAID BY AN EARLY TRAVERSE STROKE ON THE TAKEOFF SIDE OF THE MIDPOINT OF THE YARN PACKAGE LENGTH OF THE FULL PACKAGE HAS A VALUE OF AT LEAST 58, GRADUALLY ADJUSTING THE TRAVERSE IN A MANNER TO REDUCE SUCH PERCENTAGE IN SUCCEEDING TRAVERSE STROKES THROUGHOUT THE BUILDING OF AT LEAST A PART OF THE FULL PACKAGE, AND PROGRESSIVELY MOVING THE TRAVERSE REVERSAL POINTS OPPOSITE SAID TAKEOFF SIDE TOWARD SAID TAKEOFF SIDE DURING THE BUILDING OF AT LEAST THE LAST THREE-QUARTERS OF THE FULL PACKAGE WEIGHT.

United States Patent [72] Inventors Gwyniryn John Morris:

.\lichael Tayler Kirk. Pontypool. England [21] Appl. No. 724,338 [22] Filed Apr. 26, 1968 [45] Patented June 28, 1971 [731 Assignee Imperial Chemical Industries Limited London, England [32] Priority May 4, 1967 [33] Great Britain [31 20725/67 [54] YARN PACKAGE 12 Claims, 3 Drawing Figs.

[521 11.8. C1 242/176 [51] Int. Cl B65h 55/00 [50] Field of Search 242/176, 177, 178, 174,175, 26.1, 26.2, 26.3; 57/98, 99

[56] References Cited UNITED STATES PATENTS 2,764,363 9/1956 Stammwitz 242/26.2

Primary ExaminerStanley N. Gilreath Attorney-Cushman. Darby and Cushman ABSTRACT: A process for the building of a stable yarn package having a yarn takeoff end and having improved uniformity of mean takeoff tension wherein the yarn is traversed axially of the package in a succession of traverse strokes, the improvement comprising traversing the yarn during winding in a manner such that the percentage of yarnlaid by an early traverse stroke on the takeoff side of the midpoint of the yarn package length of the full package has a value of at least 58, gradually adjusting the traverse in a manner to reduce such percentage in succeeding traverse strokes {throughout the building of at least a part of the full package, and progressively moving the traverse reversal points opposite said takeoff side toward said takeoff side during the building of at least the last threequarters of the full package weight.

PATENTEU M28 19;; 3 587 996 TRAVERSE GUIDE POSITION -=CONSTRUCTION LINES TRAVERSE GUIDE POSITION MEAN -kEfifi (arbitrary umts) NORMAL LONG-SHORT PACKAGES x PACKAGES MADE Acconnme T0 PRESENT \NVENTION RESIDUAL PACKAGE WT. (o

ddmm ai m M Attorney,

vAaN PACKAGE The present invention relates to yarn packages having improved unifonnity ofmean takeoff tension.

By the term yarn package is meant an assembly of one or more turns of yarn wound onto a container such as a cylinder.

By the term yarn package length used hereinafter is meant the length of such assembly measured in a direction parallel with the long axis of said container.

By takeoff tension is meant the tension in the yarn between the yarn package and a means removing the yarn from said package when the yarn is removed in a direction substantially parallel with said long axis. It is measured as hereinafter described.

By mean takeoff tension is meant the mean of the takeoff tensions during takeoff of yarn layed on by one traverse stroke during package building.

The present invention will be described particularly, but not limitatively, with reference to a package of nylon 66 yarn wound onto a cylinder and then used in the making of knitted stockings.

In making such a package the yarn is normally wound onto a rotating cylinder by means of a guide traversing in a direction parallel with the axis of rotation of said cylinder. Variation of the traversing motion of the guide may be performed during the winding operation in three ways, namely by varying the amplitude of each traverse stroke, the positions of the traverse reversal points and the traversing speed. Such variation is usually performed continuously during package building and according to a predetermined pattern and such patterns may be quite complicated. A given traversing pattern may be repeated several times during the building of a package, often with a further pattern superimposed, and a package so produced is known as a multicycle package.

The principle ofthe present invention will be described, for clarity, with reference to a single-cycle package, that is a package during the building of which the traversing pattern is not repeated. In this illustrative description we shall also dispense with any superimposed pattern such as a gradual shortening of the traverse stroke amplitude. In practice such a gradual shortening is usually carried out in order to produce sloped package ends which sloped ends give stability to the package and reduce the danger of yarn falling off from said ends. A situation will be considered in which yarn is removed from such a simple square-ended package and fed to a stocking knitting machine. Normally, after the yarn leaves the stationary package it passes through an annular guide, called a takeoff guide, located at a distance from the takeoff end of the package and at a position on or near a projection of the long axis of the package cylinder. The takeoff end of the cylinder is often shaped, for instance rounded, in order to reduce damage to yarn rubbing on it.

The circular unwinding motion, usually taking place at high speed (for example 500 feet of yarn per minute or more may be removed), throws the yarn leaving the package outwards from said axis by centrifugal force. Owing to the rapid angular displacement of the loop of yarn between package and takeoff guide, to the eye the appearance of a balloon is produced and indeed in practice this phenomenon is known as a balloon. It will be appreciated that the aforesaid centrifugal force gives rise to a tension in the yarn. The longer the loop, that is the greater the distance between the guide and the point where the yarn leaves the package, the greater the weight of yarn in the loop and hence for a given loop angular velocity the greater the tension in the loop. If the linear speed of yarn removal is constant, this angular velocity will be determined by the diameter of the layer from which the yarn is taken. As this diameter decreases the loop angular velocity will increase. From what has been said it will be appreciated that the mean tension in the loop will tend to increase as the residual package weight decreases. This increase in tension will be further promoted by the fact that the increased angular velocity causes a greater resistance to be exerted on the yarn loop by the ambient air.

When such yarn is fed to a stocking-knitting machine the aforesaid increase in mean yarn tension is communicated to the yarn in the knitting machine and the knitted stockings tend to have smaller and smaller loops and to be shorter and shorter. The stocking manufacturer thus produces stockings of different lengths which stockings must later be matched up in pairs, a tedious and costly operation.

The takeoff tension will, of course, vary within a given layer as the yarn leaves the package at points at varying distance from the annular takeoff guide. so producing varying balloon length. However such variations are of high enough frequency for several of them to be included in one stocking and they do not in practice give unacceptable variations in appearance within a stocking or in stocking length.

The main difficulty arises from the gradual increase in mean takeoff tension in each layer as the yarn takeoff point inwardly approaches the package container.

Applicants have found that with a conventional package build most of the increase in takeoff tension occurs during removal ofapproximately the last quarter of the yarn.

Clearly a yarn package which provides a substantially uniform mean takeoff tension is desirable.

it is an object of the present invention, therefore, to provide a yarn package which gives improved uniformity of mean takeoff tension throughout the package.

Applicants have found that the increase in mean tension as the takeoff point approaches the container, which increase is due to increased mean balloon loop angular velocity, can be offset by suitably shortening the mean balloon loop length. Such shortening reduces the tension-producing effects of centrifugal force and of air resistance.

Such desirable shortening of the mean balloon loop length within a given yarn layer can be accomplished by locating more of the yarn wound on in said layer nearer to the takeoff end of the package.

Applicants have now found that said object of the present invention can be attained if during the building of a package the percentage of yarn wound on nearer the takeoff end of the package by an early traverse stroke has a value of at least 58 and such percentage is gradually reduced throughout the building ofa part or the whole of the full package weight.

The said early traverse stroke need not be the first stroke but is preferably so. In any case, the amount of yarn layed on before said early traverse stroke should not exceed 5 percent of the full package weight.

Furthermore, the percentage layed on by said early traverse stroke may be given so high a value that overcompensation of the tension increase may occur, so producing an undesirable fall in mean tension towards the container and suitable simple experimentation will be required to obtain the optimum results.

In order to produce said reduction in percentage, overlapping of yarn may take place at the traverse reversals opposite to the takeoff end. Such overlapping gives rise to takeoff tension peaks which become greater and more detrimental the greater the package weight. lt is desirable therefore to terminate such overlapping as soonas possible, consistent with attaining the build geometry necessary for accomplishing the objects of the present invention and at least before onequarter of the full package weight has been built. The traverse reversal points opposite the takeoff end are therefore moved progressively towards the takeoff end during the building of at least the last three-quarters of the full package weight.

The present invention therefore provides a process for the building of a stable yarn package having improved uniformity of mean takeofi' tension wherein the yarn is traversed axially of the package in a succession of traverse strokes, the traverse strokes being such that the percentage amount of yarn layed by an early traverse stroke on the takeoff side of the midpoint of the yarn package length of the full package has a value of at least 58 and wherein such percentage is gradually reduced throughout the building of a part or the whole of the full package and wherein the traverse reversal points opposite said takeoff side are moved progressively towards said takeoff side during the building of at least the last three-quarters of the full package weight.

The actual traverse motion pattern used in making a yarn package according to the present invention can only be determined by experiment in any given case, since it will clearly be influenced by such factors as the dimensions of the container, the total weight of the package and the obtaining of a stable package build.

However, modern yarn-winding machinery usually provides means whereby the traverse speed. the traverse stroke and the position of the traverse reversal points can be widely varied and so carrying out of the present invention will present little difficulty to those skilled in the art.

The invention will further be illustrated. in no way limitatively. by reference to the accompanying FlGS.. whereof:

FIGS. la and lb are diagrammatic representations of traverse patterns for building packages according to the present invention.

FIG. 2 is a graph illustrating the change in mean takeoff tension throughout normal long-to-short packages, i.e. packages made with constantly decreasing traverse stroke length, and packages made according to the present invention.

One way for instance in which the present invention can be carried out is to vary the traverse speed within a stroke, decreasing it as it approaches the takeoff end of the bobbin and increasing it after reversal near said takeoff end. Such deceleration and acceleration may vary from traverse-stroke to traverse-stroke and such variation may be combined with alterations in traverse stroke length and reversal point position, the object being to produce a yarn package with improved uniformity of mean takeoff tension without producing unacceptable deterioration in other package properties.

Alternatively the traverse speed may be kept constant and the stroke length and position varied, for instance as shown diagrammatically in FIGS. la and lb.

The present invention is illustrated but in no way limited by the following examples.

EXAMPLE 1 Packages were made according to the present invention, together with normal long-to-short control packages. For this, undrawn monofilament nylon 66 yarn was drawn to produce 15/1 yarn and this was wound onto 12 inch long aluminum cylinders, on the drawtwisting machine, to form 32 02. full weight packages.

The drawtwisting speed was 2,134 f.p.m., the drawn yarn had 0.32 twist and the ring rail ofthe machine was tilted 3 from the horizontal.

To make the packages according to the present invention a traverse-speed-varying device was used wherein a hydraulic valve controlled the ring rail speed. In this way the upstroke was decelerated and the downstroke accelerated. The initial velocity at the bottom was about 25 in./min. and that at the top about 5 in./min. During the building of the package the acceleration and deceleration were gradually changed so that the traverse velocity became about 20 in./min. at the bottom and about in./min. at the top. The traverse stroke length was gradually decreased from about 9% inches to about 3% inches. The full weight packages so produced had side tapers of about 5.

Takeoff tensions were measured in arbitrary units, throughout six of each type of package, using an annular takeoff guide, located 4 inches above the top of the stationary vertical package, and a yarn linear takeoff speed of 500 ft./min. The yarn contacted the tension-sensing device just beyond the takeoff guide.

With the measuring apparatus used, the takeoff tension, in arbitrary units, was continuously plotted against the length, and hence weight, of yarn removed. The areas under the tension traces were then measured on each trace using a planimeter, over five traverse cycles. at positions corresponding to EXAMPLE 2-5 Yarn packages were built according to the data given in the table below. The mean takeofi' tensions were measured as described in Example 1.

Example Process data 2 3 4 5 Yarn type, denier/n0. filaments"... 15/1 /34 15/1 100/34 Container length, inches 14% 14% 14% 14% Overall package build length, inches 12 12 12 12 Package weight, lbs (1) (i) 2 (l) Drawtwist speed, f.p.m 4, 200 2, 646 4, 200 2, 646 Yarn twist, turns per inch 0. 2 0. 25 0.2 0. 25 Ring tilt angle, degree 3 0 3 0 Traverse motion:

Up-stroke Velocity, inches/min 60 34. 2 18 48 Down-stroke Velocity, inches/min 18 48 Initial:

Top 3. 4 13.3 Bottom 18. 5 34. 2 Final:

Top 7. 1 19. 5 Bottom 13. 6 29. 4 Stroke length (inches):

Initial 12 12 10 7 At point where reversals opposite to take-oti end start to move towards take-0d end 11 11 Final 5. 4 6. 2 7 7 Percent yarn on top half of the build,

max 62 60 Mean take-0E tension change through the package build, arbitrary units 35 129 42 112 Mean take-oft tension change through the package build [or normal long-toshort package, arbitrary units 62 194 G2 127 1 Approx. 3.

2 Approx. 2%.

3 Constant velocity. 4 Accelerated.

5 Constant.

* At least 60.

While the present invention has been described with reference to the making of packages of nylon 66 yarn by winding onto a cylinder, which packages are used for stocking knitting, it will be clear to those skilled in the art that this invention can be operated with other types of yarn and yarn package.

The description of the invention also makes it clear that considerable variation in the package build can be made without departing from the spirit of the invention. For instance, the traverse stroke velocity may be accelerated or decelerated or held constant in either one direction of traverse or in both directions or combinations of such motions may be made.

We claim:

1. A process for the building of a stable yarn package having a yarn takeoff end and having improved uniformity of mean takeoff tension wherein the yarn is traversed axially of the package in a succession of traverse strokes, the improvement comprising: traversing the yarn during winding in a manner such that the percentage of yarn laid by an early traverse stroke on the takeoff side of the midpoint of the yarn package length of the full package has a value of at least 58; gradually adjusting the traverse in a manner to reduce such percentage in succeeding traverse strokes throughout the building of at least a part of the full package; and progressively moving the traverse reversal points opposite said takeoff side toward said takeoff side during the building of at least the last three-quarters of the full package weight.

2. A process as claimed in claim 1 wherein said early traverse stroke is the first stroke.

3. A process as claimed in claim 1 wherein up to 5 percent of the full package weight of yarn is layed on before the laying on of said early traverse stroke.

4. A process as claimed in claim 1 wherein the percentage of yarn layed on by said early traverse stroke is between 58 and 63 percent.

5. A process as claimed in claim 1 wherein the percentage of yarn layed on by said early traverse stroke is between 60 and 65.

6. A process as claimed in claim 1 wherein said percentage is gradually reduced during the building of up to one-half of the full package weight.

7. A process as claimed in claim 1 wherein the package is built onto a cylinder.

8. A process as claimed in claim 1 including the step of maintaining the traverse stroke velocity substantially constant in at least one direction of traverse.

9. A process as claimed in claim 1 including the step of accelerating the traverse stroke in at least one direction of traverse.

10. A process as in claim 1 including the step of decelerating the traverse stroke in at least one direction of traverse.

11. A yarn package having a yarn takeoff end comprising a plurality of wound layers of yarn, each layer being constituted by a plurality of turns of yarn, wherein the percentage of yarn in one of the innermost layers on the takeoff side of the mid point of the yarn package length of the full package has a value of at least 58, wherein the percentage of yarn in the same location in succeeding outer layers of yarn is successively less, and wherein the package is tapered in a direction away from the end opposite to its takeoff end.

12. A yarn package as in claim 11 wherein up to 5 percent of the total yarn in the package is located in layers disposed closer to the axis of the package than said one layer. 

